A Royal Caribbean cruise ship is returning to port a day early after a norovirus outbreak left hundreds of passengers and crew “gravely ill,” People reports.

The Oasis of the Seas is set to arrive at Port Canaveral in Florida on Saturday “after an episode of gastrointestinal illness” that affected. The ship set sail on Jan. 6, with planned stops in the Caribbean and Mexico.

Soon, however, passengers began to get sick. After being allowed to go ashore in Haiti on Tuesday, passengers were not allowed to leave the ship the next day in Jamaica.

As the vessel later headed toward Cozumel, Mexico, a decision was made to, instead, turn back and return to port. Initial reports said that about 300 people were ill.

But ABC reports that that number is closer to 500. Everyone aboard the Oasis will reportedly get full refunds.